Gear-shifting devices are know, e.g. from U.S. Pat. Nos. 3,362,238 and 3,394,604, wherein a shift lever or a mounting therefor is provided with a ball check enabling the indexing of that lever in its several working positions. It has also been proposed (see, for example, British Pat. No. 661,843) to provide such a mechanism with a cam disk which can be stepped by back-pedaling into successive operating positions for establishing a variety of speed ratios, albeit only in a predetermined sequence.